A vehicle starts moving along a straight line path from rest. In first t seconds it moves with an acceleration of 2 m/s² and then in next 10 seconds it moves with an acceleration of 5 m/s². The total distance travelled by the vehicle is 550 m. The value of time t is

A pumpkin weighs 7.5 N. On sub- merging it completely in water, $\frac{3}{4}$L of water gets displaced. The acceleration due to gravity at the place where the pumpkin was weighed is 10 m/s². Which one of the following is the correct value of the density of the pumpkin?

An incandescent electric bulb converts 20% of its power consumption into light, and the remaining power is dissipated as heat. The bulb's filament has a resistance of 200 Ω and 2 A current flows through it. If the bulb remains ON for 10 h and the rate of electricity charge is Rs. 5/unit, then which among the following is the correct amount for the money spent on producing light?

Which one of the following statements best defines the concept of heat?